Mining’s old guard needs strong medicine
A new report details subpar investor returns in the mining industry over the last decade, particularly big cap diversified companies which have not adapted to new realities.
- 88 – 92% recoveries for direct carbon-in-pulp and carbon-in-leach cyanidation tests at P80 = 200 mesh (75 microns).
- Gravity recoverable gold of 40-50% at a concentrate grade of 25 g/t.
- Cyanide consumption of 0.32 kg/t.
- The mean calculated head grade for the range of tests carried out was 0.78 g/t, well below the diluted resource grade of 0.91 g/t. Brazilian Gold’s metallurgical consultants anticipate an increase in recoveries at higher feed grades.
Samples were taken from nine drill holes, covering a strike length of 600 m over a vertical depth of 60 to 350 m below surface. The samples were crushed to P80 = 1.68 mm and composited into a single representative sample from which a number of 1 kg sub-samples were taken for leach and gravity recovery testwork.
São Jorge gold bearing samples have been shown to be amenable to cyanide leaching at a grind of P80 75 micron grind size. In bottle roll leach tests using this grind size, gold recovery was found to be between 88% and 92%.
Cyanide dosage optimization test work results indicated that cyanide consumption of 320 grams of cyanide per tonne of feed was required in order to achieve the highest gold recovery.
Samples were also subjected to gravity concentration prior to cyanide leaching for which the average recovery was 41% at a feed size of 75 micron P80. The gravity concentrate assayed 25 g/t. Cyanide leaching of the gravity tails product reported gold recoveries between 88 and 92%.
The free milling properties of the gold in the samples indicate that gravity concentration is viable, which should help gold extraction ahead of cyanide leaching resulting in lower cyanide consumption and shorter leach residence time.
Further testwork is planned to better define grind size versus gold recovery and to optimize leach residence time and cyanide consumption rates. Additional work will also include intense cyanide leach recovery potential of the gravity concentrate for its impact on overall gold recovery.
Ian Stalker, CEO of Brazilian Gold, commented “These results add further significant value to our ongoing work on our São Jorge project in the Tapajós region of Brazil. The metallurgical testwork has determined that gold recovery in the 90% range is possible, confirming estimations made in the PEA delivered in July 2011, and we can expect better recoveries at our predicted higher feed grades when operations commence. The ability to separate and recover gold by gravity indicates lower capital and operating costs can be expected.
As indicated by our consultants, the mean calculated head grade for the range of tests carried out was 0.78 g/t gold, well below the diluted resource grade of 0.91 g/t. Brazilian Gold’s metallurgical consultants anticipate an increase in recoveries at higher feed grades.
Based on the results, consideration will also be given to a ‘heap leach’ approach to treating our ore body.
It is also important to note our ongoing optimization of the São Jorge project by Coffey Mining (Canada) following completion of the 2011 drill campaign. The mining inventory recovered from the resource reported in the July 2011 PEA was only 49% and any further increase in the reserve will add extra dollar value to our project.”
Matt Bolu, M.Sc., P.Eng., principal of Bolu Consulting Engineering Inc. was commissioned by Brazilian Gold Corporation to review the metallurgical testwork completed by Testwork Desenvolvimentos de Processo Ltda. Mr. Bolu is a Qualified Person, as defined by National Instrument 43-101, and has approved the technical disclosure contained in this News Release.
About Brazilian Gold Corporation
Brazilian Gold is a Canadian-based public company with a focus on the acquisition, exploration and development of mineral properties in northern Brazil. The Company has title to one of the largest land packages (3,750 km2) in the Tapajós and adjacent Alta Floresta gold provinces. The land package contains green fields to more advance stage projects including the Company’s flagship São Jorge project. Rapid improvements to regional infrastructure continue to provide underlying support to Brazilian Gold’s activities in northern Brazil.
The São Jorge project contains an indicated mineral resource of 11.365 Mt grading 1.0 g/t gold (379,000 ounces of gold) and an inferred mineral resource of 20.673 Mt grading 0.8 g/t gold (558,000 ounces of gold) at a 0.3 g/t gold cut-off (Coffey Mining, June 21, 2011).
Some statements in this news release contain forward-looking information, including without limitation statements as to planned expenditures and exploration programs. These statements address future events and conditions and, as such, involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the statements. Such factors include without limitation the completion of planned expenditures, the ability to complete exploration programs on schedule and the success of exploration programs.
Neither TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or the accuracy of this news release.
